This invention relates to implements such as mower decks and the belt drive mechanisms which transmit power from a vehicle power source to the mower deck.
Conventional front mounted mower decks are coupled to the front portion of a tractor vehicle, and can be raised or lowered for adjusting the height at which grass is cut. Conventional mower decks are pivotally coupled with the vehicle such that the mower deck can pivot with respect to the vehicle about a horizontal axis. The mower is therefore allowed to ride up and down over ground undulations in close contact with the ground.
Belt drive systems are often utilized for transferring power from the vehicle power source or engine to the mower deck. Conventional belt drive systems include an output sheave coupled with an output shaft driven by the engine. A primary belt extends between the output sheave and a double pulley jacksheave. A secondary belt is operatively coupled with the jacksheave and drivingly engages a plurality of mower deck sheaves. Vertically oriented spindles rotate with the mower deck sheaves. Cutting blades are fixed for rotation with the lower ends of respective spindles for mowing vegetation. The output sheave and the mower deck sheaves are typically not positioned at the same vertical elevation or plane, and therefore the jacksheave acts to transmit the rotational power of the output sheave to the height or elevation of the mower deck sheaves.
The jacksheave of a conventional belt drive mechanism is typically carried by the mower deck. Therefore, as the deck shifts up and down during adjustments of the cutting height or when ground undulations are encountered the jacksheave carried by the deck will shift up and down with respect to the vehicle. Since the jacksheave and mower deck sheaves are both carried by the mower deck, the jacksheave and mower deck sheaves remain properly aligned when the mower deck pivots with respect to the vehicle. However, when the deck shifts vertically the jacksheave shifts vertically out of alignment with the output sheave. The primary belt must therefore extend at an angle between the output sheave and the jacksheave. The primary belt therefore engages the output sheave at an angle to the plane in which the output sheave is rotating. Also, the primary belt engages the pulley of the jacksheave at an angle to the plane in which the jacksheave pulley is rotating. As these belt angles get large, the belts can wear relatively quickly as the belt contacts the pulleys. The belt may eventually fail due to wear, causing downtime and repair expense. Also, when a belt engages a pulley at a relatively large angle the belt is more prone to jump off the pulley, causing interruption to operation.
It would therefore be desirable to provide a belt drive mechanism for driving an implement such as a mower deck and which reduces or eliminates problems associated with sheave misalignment and excessive belt angles.